1. Field of the Invention
The present invention relates to a stereophonic binaural recording or reproduction method for audio signals presented to headsets.
2. Description of the Related Art
Many stereophonic recording and reproduction methods seek to provide at the audiotory location the true auditive originality of the listening event prevailing at the recording location.
German Offenlegungsschrift 31 12 874 describes one of the methods for reproducing a sound recording and a device for carrying out the reproduction. This method makes it possible to obtain a spatial sound reproduction which is perceived to be very natural, particularly when headsets are used as the reproduction device. The method is based on supplying the sound recording to the reproduction apparatus through a reverberation producing unit which produces reverberation reflections within a period of time of approximately 50 ms after the direct sound pulse has arrived. The reverberation reflections are produced in time intervals, preferably over 2 ms, such that they are still perceived by perceived by the listener as individual reflections of strong sound. At least some of the individual reflections consist of two pulses which are separated by a direct sound pulse from a channel of the sound carrier. The first of these pulses is emitted through a channel of the reproduction apparatus which is assigned to the corresponding sound carrier channel and the second pulse is somewhat weaker and is emitted with a time delay of approximately 0.2 ms to 1 ms, preferably to 0.63 ms, relative to the first pulse through the other channel of the reproduction apparatus, wherein the reverberation reflections are attenuated in dependence on the sound frequency.
The above-described method, which is also called real time stereophony, is based on the recognition that sound fields cannot easily be transferred in their original spatial distribution to a listening room which differs from the recording room. Particularly in the case of headset reproduction in which no acoustic listening room is involved, an electroacoustically reconstructed sound field must be presented in accordance with psychoacoustic considerations. The sound material used for this purpose is spatially defined at least with respect to its recording. Thus, this method makes it possible to obtain in the reproduction a remarkable spatial effect and excellent transparency of the sound occurrence, primarily of the music occurrence, because the essential sound which is reflected having first once encountered one of the walls enclosing the room and then finally having encountered more than one wall is reconstructed in the acoustically correct time interval with subsequent reverberations. However, this method does not solve the problem of incorrect localization of the auditory event.
It is, therefore, the primary object of the present invention to provide a method for the stereophonic binaural recording or reproduction of audio signals which provides the true auditive originality at the auditory location and which, most importantly, makes possible a clear and correct localization of certain sound sources.